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iproute: Properly handle protocol level diag module absence

PATCH In review Pavel Emelyanov 3 participants 3 messages Jan 28, 2014 – Feb 10, 2014

Subsystems (2)
Networking Network drivers
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Share & tools
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Pavel Emelyanov

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#0 lore raw

PATCH 1/1 iproute: Properly handle protocol level diag module absence

When *_diag module is missing in the kernel, the ss tool should go ad read legacry /proc/* files.

This is the case when all *_diag stuff is missing, but in case the inet_diag.ko is loaded, but (tcp|udp)_diag.ko is not, the ss tool doesn't notice this and produces empty output. The reason for that is -- error from the inet_diag module (which means, that e.g. the udp_diag is missing) is reported in the NLMSG_DONE message body.

That said, we need to check the NLMSG_DONE's message return code and act respectively.

Reported-by François-Xavier Le Bail <[email protected]>
Signed-off-by Pavel Emelyanov <[email protected]>

---

misc/ss.c +8 -1
index 37dcc11..9c7d937 100644
@@ -1746,8 +1746,15 @@ again:
 			    h->nlmsg_seq != 123456)
 				goto skip_it;
 
-			if (h->nlmsg_type == NLMSG_DONE)
+			if (h->nlmsg_type == NLMSG_DONE) {
+				int *len = (int *)NLMSG_DATA(h);
+				if (*len < 0) {
+					close(fd);
+					return -1;
+				}
+
 				goto done;
+			}
 
 			if (h->nlmsg_type == NLMSG_ERROR) {
 				struct nlmsgerr *err = (struct nlmsgerr*)NLMSG_DATA(h);
Tested-by on v1 1/1
#1 lore raw
Quoted 9 lines · Pavel Emelyanov

When *_diag module is missing in the kernel, the ss tool should go ad read legacry /proc/* files.

This is the case when all *_diag stuff is missing, but in case the inet_diag.ko is loaded, but (tcp|udp)_diag.ko is not, the ss tool doesn't notice this and produces empty output. The reason for that is -- error from the inet_diag module (which means, that e.g. the udp_diag is missing) is reported in the NLMSG_DONE message body.

Quoted 7 lines

That said, we need to check the NLMSG_DONE's message return code and act respectively.

Reported-by François-Xavier Le Bail <[email protected]>
Signed-off-by Pavel Emelyanov <[email protected]>

---

Tested-by François-Xavier Le Bail <[email protected]>
#2 lore raw
In reply to Pavel Emelyanov
Quoted 9 lines · On Tue, 28 Jan 2014 21:32:00 +0400 Pavel Emelyanov <[email protected]> wrote:

When *_diag module is missing in the kernel, the ss tool should go ad read legacry /proc/* files.

This is the case when all *_diag stuff is missing, but in case the inet_diag.ko is loaded, but (tcp|udp)_diag.ko is not, the ss tool doesn't notice this and produces empty output. The reason for that is -- error from the inet_diag module (which means, that e.g. the udp_diag is missing) is reported in the NLMSG_DONE message body.

Quoted 6 lines

That said, we need to check the NLMSG_DONE's message return code and act respectively.

Reported-by François-Xavier Le Bail <[email protected]>
Signed-off-by Pavel Emelyanov <[email protected]>

Silently ignoring the error seems wrong.
The fallback is good, but we should try and report the error so that the user fixes the kernel config.